反复烧结对氧化锆支架与饰瓷结合强度的影响

Effect of repeated firing on the bond strength of zirconia core with veneering ceramics

目的研究多次烧结对牙科氧化锆陶瓷与饰面瓷双层瓷结构力学性能的影响,为临床及技工的操作提供理论依据。方法采用粉浆涂塑法将Kiss饰面瓷堆塑在直径10mm、厚1mm的氧化锆试件上,将20个试件随机分为A、B、C、D四组,按照常规烧结程序分别烧结不同次数,其中A组3次、B组5次、C组7次、D组9次。在万能材料试验机上测试试件界面的剪切强度。采用SPSS11.0统计软件对测试结果进行统计分析。使用扫描电镜(SEM)等研究试件界面的形貌。结果随着烧结次数的增加,A、B、C、D四组试件的剪切强度依次为(28.07±2.40)MPa、(31.91±1.47)MPa、(27.27±3.10)MPa、(21.68±1.51)MPa。其中,D组的剪切强度明显低于其他三组,差异具有统计学意义(P<0.05);而B组试件的剪切强度均数较A组、C组略高,差异也具有统计学意义(P<0.05);A组与C组的剪切强度均数差异无统计学差异(P>0.05)。SEM观察发现多次烧结后界面间的气孔和裂纹增多,结合性能降低。结论超过一定的烧结次数时,烧结次数的增加对氧化锆陶瓷与饰面瓷双层瓷的结合强度有影响。技工室操作时应尽量减少对氧化锆陶瓷与饰面瓷双层瓷的烧结次数。

Objectives The purpose of this study was to investigate the effect of multiple sintering on the bond strength between the veneering ceramic and dental zirconia framework. Methods Bilayered-specimens of zirconia core with veneering porcelain were made according to the manufacturer′s instruction. The specimens were randomly divided into A, B, C, D four groups, 5 specimens for each group, and sintered for different times： group A three times, group B five times, group C seven times and group D nine times. Universal testing machine was used to test the shear strength of the interface between the veneering ceramic and zirconia framework. statistical analysis was performed with SPSS 11.0 software. The interface of the porcelain veneer and zirconia framework was characterized by scanning electron microscope（SEM）. Results The values of the shear strength of group A, B, C and D were （28.07 ± 2.40）MPa, （31.91 ± 1.47）MPa, （27.27 ± 3.10）MPa, and （21.68 ± 1.51）MPa respectively. The shear strength of group D was significantly lower than that of group A, B and C （P 〈 0.05）. However, the shear strength of group B is significantly higher than that of group A and C （P 〈 0.05）. There is no significant difference （P 〉 0.05） between group A and C. Under the SEM, more voids and cracks were observed to emerge on the interface with the increase of sintering time. Conclusions Above a certain limit, the increase of sintering time has a negative affect on the bond strength between the veneering porcelain and zirconia framework. The time of sintering should be properly controlled.